VIT Engineering VIT Engineering Solved Paper-2014

  • question_answer
    A battery is charged at a potential of 15 V in 8 h when the current flowing is 10A. The battery on discharge supplies a current of 5A for 15 h. The mean terminal voltage during discharge is 14V. The watt-hour efficiency of battery is

    A) 80% 

    B)                                        90%

    C) 87.5%                                   

    D) 82.5%  

    Correct Answer: C

    Solution :

    The power of the battery, when charged is given by                      \[M=\frac{1000\times {{k}_{b}}\times w}{W\times \Delta {{T}_{b}}}\] The electrical energy dissipated is given by                        \[\Delta {{T}_{b}}=\frac{1000\times {{k}_{b}}\times 10}{100\times 100}\] \[{{E}_{1}}={{V}_{1}}{{l}_{1}}{{t}_{1}}=15\times 10\times 8\]                 \[=1200Wh\] Similarly, the electrical energy dissipated during the discharge of battery is given by                                \[\left( {{\text{R}}_{\text{1}}}\text{-X  and  }{{\text{R}}_{\text{2}}}\text{-X} \right)\] The electrical energy dissipated is given by \[{{E}_{2}}={{V}_{2}}{{l}_{2}}{{t}_{2}}\] \[=14\times 5\times 15\] \[=1050Wh\] Similarly, the electrical energy dissipated during the discharge of battery is given by                                  \[\begin{align}   & OO \\  & |||| \\  & C{{H}_{3}}-C-C{{H}_{2}}-C-O{{C}_{2}}{{H}_{5}}\rightleftharpoons  \\  & \left( keto \right) \\ \end{align}\]                                   \[\begin{align}   & OHO \\  & ||| \\  & C{{H}_{3}}-C=CH-C-O{{C}_{2}}{{H}_{5}} \\  & \left( enol \right) \\ \end{align}\]                                  = 1050 Wh Hence, watt-hour efficiency of the battery is given by                                \[N{{a}_{2}}S\]                               \[N{{a}_{2}}S+{{\left( C{{H}_{3}}COO \right)}_{2}}Pb\to \]


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